Automatic real-time tracking and stabilization of magnetic islands in a Tokamak using temperature fluctuations and ECW power

Berrino, J.; Cirant, S.; Gandini, F.; Granucci, G.; Lazzaro, E.; Jannone, F.; Smeulders, P.; D′Antona, G.

doi:10.1109/tns.2006.875156

Cited by 25 publications

(14 citation statements)

References 3 publications

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“…The location in normalized radius of this mode can be inferred from temperature fluctuation measurements at the mode frequency of the NTM. The phase jump of the fluctuation is related to the change in phase of the temperature fluctuation around the NTM magnetic island [2,5,53]. These measurements combined with the magnetic equilibrium indicate that the NTM is located at a normalized radius of about 0.6.…”

Section: Ntm Stabilization Experimentsmentioning

confidence: 99%

A data acquisition system for real-time magnetic equilibrium reconstruction on ASDEX Upgrade and its application to NTM stabilization experiments

Giannone

Reich

Maraschek

et al. 2013

Fusion Engineering and Design

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The pre-emptive stabilization of a neoclassical tearing mode, NTM, requires the calculation of the tokamak magnetic equilibrium in real-time. A launcher mirror is positioned to deposit electron cyclotron current drive on the rational surface where the NTM should appear. A real-time Grad-Shafranov solver using constraints from magnetic probe, flux loop and Motional Stark Effect measurements has been developed to locate these rational surfaces and deliver this information to the mirror controller in real-time. A novel algorithm significantly reduces the number of operations required in the first and second step of the solver. Contour integrals are carried out to calculate the q profile as a function of normalized radius and the rational surfaces are found by spline interpolation. A cycle time of 0.6 ms for calculating two tokamak equilibria in parallel using four current basis functions with magnetic constraints only and using six current basis functions with magnetic and MSE constraints has been achieved. Using these tools, pre-emptive stabilization

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Section: Ntm Stabilization Experimentsmentioning

confidence: 99%

A data acquisition system for real-time magnetic equilibrium reconstruction on ASDEX Upgrade and its application to NTM stabilization experiments

Giannone

Reich

Maraschek

et al. 2013

Fusion Engineering and Design

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“…As can be seen, the mode remains suppressed during the subsequent β Ν -ramp up to the ideal MHD stability limit, but re-strikes immediately after ECCD is turned off. Finally, we note that also an algorithm that recognizes the occurrence of the mode and acts on the ECCD will be needed; this has been demonstrated recently in the FTU tokamak where gyrotrons were run in modulated mode with low duty cycle and switched to high duty cycle modulation when the mode was detected [40]. The modulated operation was used to measure the ECCD deposition location by ECE, while the resonant surface was detected using an ECE correlation method.…”

Section: Feedback Controlled Deposition For Ntm Suppression By Eccdmentioning

confidence: 97%

Recent Experimental Progress in Electron Cyclotron Resonance Heating and Electron Cyclotron Current Drive in Magnetically Confined Fusion Plasmas

Zohm

2007

Fusion Science and Technology

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A review of recent experimental results in the area of ECRH and ECCD is given. Special emphasis is put on the recent developments of new schemes in which EC waves can heat and drive current in magnetically confined fusion plasmas. These comprise scenarios to overcome the density cutoff experienced in application of the classical O1 and X2 scheme as well as to increase the current drive efficiency of EC waves while maintaining their good localization. In particular, we discuss recent experimental progress in tokamaks, stellarators and spherical tori in the areas of the O2, X3 and EBW schemes (mostly OXB scheme) as well as experiments in which the combination of ECCD with Lower Hybrid Current Drive (LHCD) leads to a synergetic increase of the ECCD efficiency. A particular application of ECCD that has recently received a lot of attention and is therefore reviewed in this paper is the suppression of Neoclassical Tearing Modes (NTMs) by ECCD. We show that the theoretically predicted requirements for ECCD in terms of deposition (maximising the ECCD driven current density) and injection in phase with the O-point of the magnetic island associated with the NTM (which is needed when the island width falls below the deposition width) have been verified experimentally. Also, many of the elements needed for constructing a reliable, feedback controlled NTM suppression system for ITER based on ECCD have now been demonstrated experimentally and the next step, which is their integration into a reliable scheme, is well within reach.

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“…A widespread method to retrieve the profile of absorbed power is to analyze the plasma response to modulations of the externally launched power. Analysis techniques such as the singular value decomposition (SVD), the fast Fourier transform (FFT) and the correlation of the response signal with the modulation waveform give satisfactory results in heating and transport studies when the conditions are stationary and the MHD activity amplitude is moderate [1] [2] [3].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Power Deposition Detection of Two EC Beams with the BIS Analysis in Moving TCV Plasmas

Curchod¹,

Pochelon²,

Decker³

et al. 2009

AIP Conference Proceedings

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Abstract. Modulation of power amplitude is a widespread to determine the radial absorption profile of externally launched power in fusion plasmas. There are many techniques to analyze the plasma response to such a modulation. The break-in-slope (BIS) analysis can draw an estimated power deposition profile for each power step up. In this paper, the BIS analysis is used to monitor the power deposition location of one or two EC power beams simultaneously in a non-stationary plasma being displaced vertically in the TCV tokamak vessel. Except from radial discrepancies, the results have high time resolution and compare well with simulations from the R2D2-C3PO-LUKE ray-tracing and Fokker-Planck code suite.

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Automatic real-time tracking and stabilization of magnetic islands in a Tokamak using temperature fluctuations and ECW power

Cited by 25 publications

References 3 publications

A data acquisition system for real-time magnetic equilibrium reconstruction on ASDEX Upgrade and its application to NTM stabilization experiments

A data acquisition system for real-time magnetic equilibrium reconstruction on ASDEX Upgrade and its application to NTM stabilization experiments

Recent Experimental Progress in Electron Cyclotron Resonance Heating and Electron Cyclotron Current Drive in Magnetically Confined Fusion Plasmas

Simultaneous Power Deposition Detection of Two EC Beams with the BIS Analysis in Moving TCV Plasmas

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